MGE Energy Inc Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Statement of Other Comprehensive Income [Abstract]
Net Income	$ 14,077	$ 24,353	$ 13,891	$ 22,584	$ 10,486	$ 23,642	$ 14,270	$ 16,048	$ 74,905		$ 64,446		$ 60,928
Other comprehensive income/(loss), net of tax:
Unrealized gain (loss) on available for sale securities, net of tax									283	[1]	(18)	[2]	(15)	[3]
Reclassification of realized gain on available-for-sale securities, net of tax									0	[4]	0	[4]	(15)	[3]
Comprehensive Income									$ 75,188		$ 64,428		$ 60,898

[1] Net of $189 tax

[2] Net of $12 tax

[3] Net of $10 tax

[4] Net of $0 tax